The present invention relates to a novel insecticidal composition for the eradication of harmful wood eating insects and comprising a known insecticide in admixture with isobornyl thiocyanoethyl ether (referred to herein as "IBTE").
Wood eating insects, such as termites, powderpost beetles (Lyctidae), lesser grain borers (Bostrichidae), drugstore beetles (Anobiidae), and longhorn beetles (Cerambycidae), cause considerable economic loss in many parts of the world. Although many different compounds have been proposed for use in their eradication, none has found complete acceptance for various reasons.
Traditionally, the active ingredient used for exterminating harmful wood eating insects such as those referred to above has been an inorganic compound (such as arsenic, arsenic pentoxide, arsenic trioxide, sodium hydrogen arsenate, chrome oxide, potassium dichromate, sodium dichromate, copper carbonate hydroxide, copper chloride, copper sulfate, sodium fluoride, ammonium fluoride, sodium silicofluoride, sodium borofluoride, boric acid or borax) or an organochlorine compound, such as chloronaphthalene, DDT, BHC, linden, dieldrin or chlordane. These compounds are frequently used because of their excellent stability and residual effect in wood and their low cost.
However, these compounds are highly toxic, and organochlorine compounds, in particular, are stable in the environment, for example in the soil. They are also very persistent in the human and animal body, and so, once they have entered the food chain, for example in the fat in fish or shellfish, they remain in the ecosystem, where their presence has become a problem. The manufacture, sale, import, and the like of these compounds are restricted in many countries, and most of them are prohibited from being used.
In place of these compounds, organophosphorus compounds, such as chlorpyrifos, pyridaphenethion, phoxim, fenitrothion, and chlorvinphos, and carbamate compounds, such as propoxur, fenobcarb, and carbaryl, have been used as agents for exterminating harmful wood eating insects.
However, organophosphorus compounds and carbamate compounds have the disadvantages that they have unpleasant odors, and that they are highly toxic, unstable to alkalis, unstable to soil bacteria and unstable to sunlight. Moreover, they must be used at a relatively high concentration (1% or more). Microcapsulation and similar procedures have been attempted to overcome these disadvantages, but this results in the problem of higher cost.
Recently, pyrethroid compounds, such as allethrin or permethrin, pyrethroid-like compounds, such as etofenprox. or silafluofen, and nicotinic acid compounds bound to nitroimidazolidylidene amine, such as imidacloprid, which have a chemical structure completely different from those of the forgoing compounds, have been used as agents for exterminating harmful wood eating insects. These pyrethroid compounds, pyrethroid-like compounds and imidacloprid are highly effective but have the disadvantage of high cost.
Japanese Patent Application Laid-Open No. Hei-7-69819 discloses the use of isobornyl thiocyanoalkyl ethers, including IBTE, for exterminating house dust mites, such as Acaridaes. Further, Japanese Patent Application Laid-Open No. Sho-46-34420 discloses that IBTE has an insecticidal effect on harmful insects such as flies, mosquitoes and cockroaches. However, IBTE is not been known to be effective for exterminating harmful wood eating insects such as termites. Indeed, as is shown hereafter, by itself, it has very little effect on such insects.